const path = require('path')

console.log(path.extname('index.html'))
// 返回: '.html'

console.log(path.extname('index.coffee.md'));
// 返回: '.md'

console.log(path.extname('index.'));
// 返回: '.'

console.log(path.extname('index'));
// 返回: ''

console.log(path.extname('.index'));
// 返回: ''

console.log(path.extname('a.index'));
// 返回: '.index'

console.log(path.extname('.index.md'));
// 返回: '.md'

console.log(path.resolve('/foo', '/bar', 'baz'));

console.log(path.resolve());

console.log(path.resolve('/foo/bar', './baz', './baz2'));

console.log(path.resolve('wwwroot', 'static_files/png/', '../gif/image.gif'));
console.log(path.join('wwwroot', 'static_files/png/', '../gif/image.gif'));

console.log(path.sep);
